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authorDenys Vlasenko <vda.linux@googlemail.com>2014-02-03 17:03:42 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2014-02-03 17:03:42 (GMT)
commite4785ca653d0e219926692c229673b2c1b8d6ac4 (patch)
tree69fc8a0a892bde0a0a9c83adf7567bbcbc8a9f74
parentfe8390e0fe7106aed9f586b3cf08215effc4450b (diff)
downloadbusybox-e4785ca653d0e219926692c229673b2c1b8d6ac4.tar.gz
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udhcpc: don't use BPF filter, users report problems (bugs 4598, 6746)
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--networking/udhcp/dhcpc.c93
1 files changed, 46 insertions, 47 deletions
diff --git a/networking/udhcp/dhcpc.c b/networking/udhcp/dhcpc.c
index 8dee916..ee19f55 100644
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -976,53 +976,6 @@ static int udhcp_raw_socket(int ifindex)
int fd;
struct sockaddr_ll sock;
- /*
- * Comment:
- *
- * I've selected not to see LL header, so BPF doesn't see it, too.
- * The filter may also pass non-IP and non-ARP packets, but we do
- * a more complete check when receiving the message in userspace.
- *
- * and filter shamelessly stolen from:
- *
- * http://www.flamewarmaster.de/software/dhcpclient/
- *
- * There are a few other interesting ideas on that page (look under
- * "Motivation"). Use of netlink events is most interesting. Think
- * of various network servers listening for events and reconfiguring.
- * That would obsolete sending HUP signals and/or make use of restarts.
- *
- * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
- * License: GPL v2.
- *
- * TODO: make conditional?
- */
- static const struct sock_filter filter_instr[] = {
- /* load 9th byte (protocol) */
- BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
- /* jump to L1 if it is IPPROTO_UDP, else to L4 */
- BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
- /* L1: load halfword from offset 6 (flags and frag offset) */
- BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
- /* jump to L4 if any bits in frag offset field are set, else to L2 */
- BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
- /* L2: skip IP header (load index reg with header len) */
- BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
- /* load udp destination port from halfword[header_len + 2] */
- BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
- /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
- BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
- /* L3: accept packet */
- BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
- /* L4: discard packet */
- BPF_STMT(BPF_RET|BPF_K, 0),
- };
- static const struct sock_fprog filter_prog = {
- .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
- /* casting const away: */
- .filter = (struct sock_filter *) filter_instr,
- };
-
log1("Opening raw socket on ifindex %d", ifindex); //log2?
fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
@@ -1033,13 +986,59 @@ static int udhcp_raw_socket(int ifindex)
sock.sll_ifindex = ifindex;
xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
+#if 0 /* Several users reported breakage when BPF filter is used */
if (CLIENT_PORT == 68) {
/* Use only if standard port is in use */
+ /*
+ * I've selected not to see LL header, so BPF doesn't see it, too.
+ * The filter may also pass non-IP and non-ARP packets, but we do
+ * a more complete check when receiving the message in userspace.
+ *
+ * and filter shamelessly stolen from:
+ *
+ * http://www.flamewarmaster.de/software/dhcpclient/
+ *
+ * There are a few other interesting ideas on that page (look under
+ * "Motivation"). Use of netlink events is most interesting. Think
+ * of various network servers listening for events and reconfiguring.
+ * That would obsolete sending HUP signals and/or make use of restarts.
+ *
+ * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
+ * License: GPL v2.
+ *
+ * TODO: make conditional?
+ */
+ static const struct sock_filter filter_instr[] = {
+ /* load 9th byte (protocol) */
+ BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
+ /* jump to L1 if it is IPPROTO_UDP, else to L4 */
+ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
+ /* L1: load halfword from offset 6 (flags and frag offset) */
+ BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
+ /* jump to L4 if any bits in frag offset field are set, else to L2 */
+ BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
+ /* L2: skip IP header (load index reg with header len) */
+ BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
+ /* load udp destination port from halfword[header_len + 2] */
+ BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
+ /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
+ BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
+ /* L3: accept packet */
+ BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
+ /* L4: discard packet */
+ BPF_STMT(BPF_RET|BPF_K, 0),
+ };
+ static const struct sock_fprog filter_prog = {
+ .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
+ /* casting const away: */
+ .filter = (struct sock_filter *) filter_instr,
+ };
/* Ignoring error (kernel may lack support for this) */
if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
sizeof(filter_prog)) >= 0)
log1("Attached filter to raw socket fd"); // log?
}
+#endif
if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
&const_int_1, sizeof(int)) < 0